The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture to generate drive torque. The combustion process generates exhaust that is exhausted from the engine to the atmosphere. The exhaust contains nitrogen oxides (NOx), carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), and particulates. An exhaust system treats the exhaust to reduce emissions prior to being released to the atmosphere.
In an exemplary exhaust system, a dosing system injects a dosing agent (e.g., urea) into the exhaust upstream of a selective catalytic reduction (SCR) catalyst. The dosing agent breaks down to form ammonia (NH3) that is stored in the SCR catalyst. NH3 stored in the SCR catalyst reacts with NOx to form nitrogen (N2) and water (H2O), which reduces the NOx levels released to the atmosphere.